I am pretty happy with the talk, which was a bit strange for me, since I get to talk about some of the downside of optimizations, rather then talking about the various specific optimizations. It looked like the audience liked the talk (I hope), so the results seems positive

Hi Ilia, nice slides. I think the statement that the database layer is often a bottleneck is true... most of the time. However, I have also coded apps in which the HTML rendering accounted for >80% of time, and the cost of SQL was small by comparison. So there are exceptions. The best advice is to take profiling measurements, no matter how certain you are of assumptions!

I have found that people very often micro optimize, perhaps it's because I mostly know people who take courses that deal with low-level stuff such compilers, but they transfer those habits to a high-end language such as PHP and fret about silly thing such as " versus ' or while versus for...

The slides are pretty good but the "then/than" mishaps really annoy me.